The driving state determination processing method is well known in that the traveling information of a vehicle, especially a change in vehicle speed and a tendency in a time period of change, is used to analyze the traveling state of the vehicle and determine the driving state of the driver (see, e.g., Patent Literature 1).
FIG. 13 illustrates the driving state determination processing device described in Patent Literature 1. The driving state determination processing device (in-vehicle device) 901 includes a vehicle speed sensor 911, a road type determination unit 912, an in-vehicle storage device 913, a traveling state determination unit 914, a determination condition setting unit 915 and a portable storage medium 916. The driving state determination processing device 901 determines the driving state of the traveling vehicle 902 and informs the driver of the traveling vehicle 902 about the determination result 917 through a sound or an image. The traveling state determination unit 914 includes a moving average calculation unit 941 and a low level of consciousness determination unit 942.
The vehicle speed sensor 911 detects the speed of the traveling vehicle 902. The road type determination unit 912 determines the type of road where the traveling vehicle 902 is running on the basis of the speed detected by the vehicle speed sensor 911, and if the type of road is targeted, the speed and acquisition time is stored in the in-vehicle storage device 913.
The traveling state determination unit 914 calculates the average speed and the acceleration within a predetermined section from the vehicle speed stored in the in-vehicle storage device 913, holds the average speed and acceleration with the acquisition time, and extracts a time point where the acceleration is reversed from the sign at the last time point. With respect to the section containing the extracted time point where the sign of the acceleration changes plus-minus-plus, the traveling state determination unit 914 determines whether the time length of the section is within a predetermined time period and whether the difference between the maximum speed and the minimum speed within the extracted section is within a predetermined range. If the result of the determination is positive, the traveling state determination unit 914 determines that the section is a single waveform section representing a low level of consciousness and outputs the determination result 917.    Patent Literature 1: Unexamined Japanese Patent Application KOKAI Publication No. 2004-234418